<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<link rel="stylesheet" href="./css/index.css">
<script src="./js/index.js"></script>

<body>
    <center>
        <div id="div">
            <span id="screen"></span>
            <ul id="btn">
                <li class="brown">c</li>
                <li class="brown">%</li>
                <li class="brown">÷</li>
                <li class="brown">×</li>
                <li class="black">7</li>
                <li class="black">8</li>
                <li class="black">9</li>
                <li class="brown">-</li>
                <li class="black">4</li>
                <li class="black">5</li>
                <li class="black">6</li>
                <li class="brown">+</li>
                <li class="black">1</li>
                <li class="black">2</li>
                <li class="black">3</li>
                <li class="zero">0</li>
                <li class="black">.</li>
                <li>=</li>
            </ul>
        </div>
    </center>
</body>

</html>